Remember doing research in high school or college? After finding a book in the library you always photocopied two parts of it. First the content you needed for your research project, second the title page of the book so you could cite your source later.
Research on the internet isn't so straight forward if you are using an iPad or laptop. You can book mark sites you like, but you can't annotate them or highlight key passages. If you copy and paste the text of the article you also have to remember to copy the URL of the site.